A common type of glassware forming machine is the so called individual section or I.S. machine which comprises a bank of separate sections which are caused to operate in staggered time relationship one with another so that each section in turn produces glassware. I.S. machines comprising 10, 12 or even more sections are now common place.
A section of an I.S. machine normally comprises two sets of moulds, each set comprising one, two three or four pairs of mould halves, one set being adapted for forming parisons from gobs of molten glass delivered to the machine, the other set being adapted for forming blown containers from the parison. The mechanisms for moving these mould halves between open and closed conditions may either move them about a vertical pivot point, thus moving the mould halves arcuately, or may move them with parallel motion. In many ways a parallel movement of the mould halves is preferable--it is easy to provide for consistent conditions in the mould halves. However parallel mould mechanisms are generally more expensive than arcuate mould mechanism, in particular because of the need to ensure the necessary rigidity of the system.
In U.S. Pat. No. 4,009,018 a parallel mould mechanism is described. This mechanism comprises two mould arms each comprising one or more supports for a mould half and three transverse rods mounted in a frame member. Each mould arm is mounted for sliding movement on two of these mould members, having a long sleeve slidably mounted on one transverse rod (thus to give transverse rigidity to the mould arm, and a short sleeve slidably mounted on another transverse rod, which rod also has a short sleeve forming part of the other mould arm slidably mounted on it. The combination of two sleeves mounted on the two rods determines the vertical position of the mould arm. Not only is this construction expensive to manufacture, but the parts require to be manufactured to very close tolerances to ensure that the vertical positions of the mould arms are correct as effectively no adjustment of these positions can be effected.
It is one of the objects of the present invention to provide a parallel mould mechanism of a cheaper and more convenient construction.